1. Field of the Invention
The present invention relates to an image forming device, such as a copying machine, a printer and a facsimile machine.
2. Description of the Related Art
A known electrophotographic image forming device forms an electrostatic latent image by charging and exposing a surface of an image carrier such as a photoconductive drum, visualizes the electrostatic latent image by adhering toner to the electrostatic latent image, and transfers the visualized image onto paper. In such a known image forming device, a replacement timing of each component is set previously. In accordance with a number-of-sheets of paper on which an image is formed or an operation time of the image forming device, a determination is made as to whether or not each component of the imagine forming device has reached a replacement timing, i.e., a time when a component should be replaced. When the replacement timing has been reached, such a fact is displayed to be confirmed by a user.
One conventional device includes a detection display controller, which detects presence or an absence of a periodically replaced component that has reached a duration warning value among each components group that is grouped according to a certain condition. When a component that has reached the duration warning value belongs to a first components group having a shortest duration conversion value, the controller compares a value of a number of times that the first components group is replaced with a value multiplied by an integer relating to a duration conversion value of a second components group. When both values do not correspond with one another, only a replacement instruction of the first components group having the shortest duration conversion value is displayed. When both values correspond with one another, the controller simultaneously displays a replacement instruction of the first components group having the shortest duration conversion value and a replacement instruction of the second components group. Meanwhile, when the periodically replaced component that has reached the duration warning value belongs to the second components group, the controller simultaneously displays the replacement instruction of the second components group and a replacement instruction of the first components group having a duration conversion value shorter than the second components group.
In the above-described conventional device, even when at least one periodically replaced component among a plurality of components groups reaches a replacement warning value, other periodically replaced components may not have reached a duration warning value yet. In such a case, a replacement instruction of such a components group is displayed and all components belonging to such a components group are replaced collectively. Therefore, although a replacement process can be carried out efficiently when the photoconductive drum is replaced with a new photoconductive drum and an image forming process is carried out by using the new photoconductive drum and an old developing unit, which may be close to its replacement timing, the developing unit is influenced by a charging electric potential of the new photoconductive drum. As a result, a deterioration of an image quality, such as a foggy image, is prone to occur.